A pro-Russian militiaman holds a piece of paper as he guards a barricade in front of the flag of the so-called Donetsk Republic outside a regional police building in Ukrainian city of Slavyansk on Monday. Ukraine's latest ultimatum to pro-Kremlin militias who have seized buildings across a swath of the separatist east expired the same day without any sign that the gunmen are ready to give in. | AFP-JIJI

HORLIVKA, UKRAINE – Ukraine’s acting President Oleksandr Turchynov on Monday called for the deployment of United Nations peacekeeping troops in the east of the country, where pro-Russian insurgents have occupied buildings in nearly 10 cities.

In a telephone conversation with U.N. Secretary-General Ban Ki-moon, Turchynov suggested that an “anti-terrorist operation” could be conducted jointly by Ukrainian security forces and U.N. peacekeepers, according to the presidential web site.

Peacekeepers, however, would have to be authorized by the U.N. Security Council, in which Russia holds a veto.

The request comes from a government that has proved powerless to reign in separatists in the Russian-speaking east of the country, where insurgents have been occupying government offices in cities for the past week. A deadline for the insurgents to give up weapons and vacate the brigands, set by Turchynov, passed Monday morning without any visible action.

Instead, violence continued. A pro-Russian mob stormed a police station in yet another city near the Russian border, while gunmen took control of a military airport.

The Kiev government and Western officials accuse Russia of instigating the unrest and of deploying armed Russian agents to carry them out.

During the storming of a police station in the city of Horlivka earlier Monday, one man identified himself as a lieutenant colonel in the Russian army.

The events in Horlivka were the latest sign of trouble in Russian-speaking eastern and southern regions, in which pro-Russian gunmen have seized or blocked government buildings in at least nine cities demanding more autonomy from the central government and closer ties with Russia. Later in the day, armed men in masks also seized control of a military airport outside the city Slovyansk, also in the Donetsk region.

The developments came as European Union foreign ministers met in Luxembourg to consider further sanctions against Russia, and three days ahead of a scheduled conference in Geneva involving diplomats from the United States, Russia, the European Union, Ukraine and Switzerland, which is intended to seek ways of defusing tensions.